Engine misfiring

[spandit]

Well, banter and innuendo (no, in your endo etc.), my thermometer arrived this morning.

Finally got round to playing with the engine this afternoon.

Before cranking, all the exhausts were reading the same (about -2ºC - which shows that the calibration is wrong as it's not THAT cold, but never mind).

A few seconds of running later and 2,3 & 4 were all climbing past 80ºC but cylinder 1 had barely moved (I'd expect a bit of conducted heat from cylinder 4 as they share the same manifold)

After a minute or so, 2,3 & 4 were well above 100ºC and climbing but 1 still hadn't budged above about 5ºC

So, whipped the plug out and sure enough it was wet and a bit black. Screwed in my compression tester and cranked again (disconnected the ignition) - gauge didn't move. Fortunately, I didn't panic and remembered that my compression tester is crap and by holding my finger over the spark plug hole, there was plenty of compression.

I then reconnected the ignition (I can just unplug the coilpack) and held the #1 spark plug against the engine. It sparked normally, so not a faulty plug (I cross checked it with a known good one).

I then turned my attention to the cut-off solenoids. Sure enough, #1 didn't click (when it definitely had before). I recall reading that these supply fuel at idle. I fired the engine up again and held the revs at 2,000rpm for a bit. Sounded a lot smoother and the thermometer indicated that #1 was firing again as the temperature quickly rose to the same as the other cylinders. This is consistent with an idle fuelling problem.

I took the #1 and #2 solenoids out to compare. #2 clicked with each connector but #1 clicked with neither. However, it came back into life again. I again screwed it into the carb and started the engine again. Idle did seem a bit better but very lumpy.

Now thinking it's a fuelling problem - will take the jets out of the carb and give them a clean. Think I'd better invest in a sync tool or find someone who knows how to tune these things. At least I don't think it's a compression problem as wasn't looking forward to buying new rings/pistons etc.

Is it possible to bypass the fuel cutoff solenoids?

[edzz]

Is it possible to bypass the fuel cutoff solenoids?

The fuel cut offs could be eliminated. My understanding is their purpose is to help shut down the engine when the ignition is shut off.
The Pinz by design tends to run richer than most motors; this increases carbon buildup especially at low rpm resulting in a greater likelihood of dieseling on shut down than most vehicles.
If you look at the zenith carbs used in the Porsche 956 I believe you will find a lack of fuel shutoff valves.
As always it’s your choice you can repair to the original design or reinvent the wheel.